Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL

This 90-day repeated-dose inhalation toxicology study of brake-dust (BD) (brakes manufactured with chrysotile) in rats provides a comprehensive understanding of the biokinetics and potential toxicology in the lung and pleura. Exposure was 6 h/d, 5d/wk., 13wks followed by lifetime observation (~20 % survival). Control groups included a particle control (TiO₂), chrysotile, commercial crocidolite and amosite asbestos. Aerosol fiber distributions of the chrysotile, crocidolite and amosite were similar (fibers L > 20 μm/cm³: chrysotile-Low/High 29/72; crocidolite 24; amosite 47 fibers/cm³; WHO-fibers/cm³: chrysotile-Low/High 119/233; crocidolite 181; amosite 281 fibers/cm³). The number of particles/cm³ in the BD was similar to that in the chrysotile, crocidolite & amosite exposures (BD 470-715; chrysotile 495-614; crocidolite 415; amosite 417 particles/cm³). In the BD groups, few fibers L > 20 μm were observed in the lungs at the end of exposure and no fibers L > 20 μm at 90d post exposure. In the chrysotile groups, means of 204,000 and 290,000 fibers(L > 20 μm)/lung were measured at 89d. By 180d, means of 1 and 3.9 fibers were counted on the filter corresponding to 14,000 and 55,000 fibers(L > 20 μm)/lung. In the crocidolite and amosite groups mean lung concentrations were 9,055,000 and 11,645,000 fibers(L > 20 μm)/lung at 89d. At 180d the means remained similar with 8,026,000 and 11,591,000 fibers(L > 20 μm)/lung representing 10-13% of the total lung fibers. BAL determined the total number of macrophages, lymphocytes, neutrophils, eosinophils, epithelial-cells and IL-1 beta, TNF-alpha and TGF-beta. At the moderate aerosol concentrations used in this study, neutrophil counts increased ~5 fold in the amphibole asbestos exposure groups. All other groups and parameters showed no important differences at these exposure concentrations. The exposure and lung burden results provide a sound basis for assessing the potential toxicity of the brake dust in comparison to the TiO2 particle control and the chrysotile, crocidolite and amosite asbestos control groups. The BAL results provide an initial indication of the differential response. Part 2 presents the presentation and discussion of the histopathological and confocal microscopy findings in this study through 90 days post exposure.

Evaluation of the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 2: Histopathological examination, Confocal microscopy and collagen quantification of the lung and pleural cavity

The interim results from this 90-day multi-dose, inhalation toxicology study with life-time post-exposure observation has shown an important fundamental difference in persistence and pathological response in the lung between brake dust derived from brake-pads manufactured with chrysotile, TiO₂ or chrysotile alone in comparison to the amphiboles, crocidolite and amosite asbestos. In the brake dust exposure groups no significant pathological response was observed at any time. Slight macrophage accumulation of particles was noted. Wagner-scores, were from 1 to 2 (1 = air-control group) and were similar to the TiO₂ group. Chrysotile being biodegradable, shows a weakening of its matrix and breaking into short fibers & particles that can be cleared by alveolar macrophages and continued dissolution. In the chrysotile exposure groups, particle laden macrophage accumulation was noted leading to a slight interstitial inflammatory response (Wagner-score 1-3). There was no peribronchiolar inflammation and occasional very slight interstitial fibrosis. The histopathology and the confocal analyses clearly differentiate the pathological response from amphibole asbestos, crocidolite and amosite, compared to that from the brake dust and chrysotile. Both crocidolite and amosite induced persistent inflammation, microgranulomas, and fibrosis (Wagner-scores 4), which persisted through the post exposure period. The confocal microscopy of the lung and snap-frozen chestwalls quantified the extensive inflammatory response and collagen development in the lung and on the visceral and parietal surfaces. The interim results reported here, provide a clear basis for differentiating the effects from brake dust exposure from those following amphibole asbestos exposure. The subsequent results through life-time post-exposure will follow.

Evaluation of the fate and pathological response in the lung and pleura of brake dust alone and in combination with added chrysotile compared to crocidolite asbestos following short-term inhalation exposure

This study was designed to provide an understanding of the biokinetics and potential toxicology in the lung and pleura following inhalation of brake dust following short term exposure in rats. The deposition, translocation and pathological response of brake-dust derived from brake pads manufactured with chrysotile were evaluated in comparison to the amphibole, crocidolite asbestos. Rats were exposed by inhalation 6h/day for 5 days to either brake-dust obtained by sanding of brake-drums manufactured with chrysotile, a mixture of chrysotile and the brake-dust or crocidolite asbestos. The chrysotile fibers were relatively biosoluble whereas the crocidolite asbestos fibers persisted through the life-time of the animal. This was reflected in the lung and the pleura where no significant pathological response was observed at any time point in the brake dust or chrysotile/brake dust exposure groups through 365 days post exposure. In contrast, crocidolite asbestos produced a rapid inflammatory response in the lung parenchyma and the pleura, inducing a significant increase in fibrotic response in both of these compartments. Crocidolite fibers were observed embedded in the diaphragm with activated mesothelial cells immediately after cessation of exposure. While no chrysotile fibers were found in the mediastinal lymph nodes, crocidolite fibers of up to 35 μm were observed. These results provide support that brake-dust derived from chrysotile containing brake drums would not initiate a pathological response in the lung or the pleural cavity following short term inhalation.

Quantification of the pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite-asbestos following short-term inhalation exposure

The marked difference in biopersistence and pathological response between chrysotile and amphibole asbestos has been well documented. This study is unique in that it has examined a commercial chrysotile product that was used as a joint compound. The pathological response was quantified in the lung and translocation of fibers to and pathological response in the pleural cavity determined. This paper presents the final results from the study. Rats were exposed by inhalation 6 h/day for 5 days to a well-defined fiber aerosol. Subgroups were examined through 1 year. The translocation to and pathological response in the pleura was examined by scanning electron microscopy and confocal microscopy (CM) using noninvasive methods.The number and size of fibers was quantified using transmission electron microscopy and CM. This is the first study to use such techniques to characterize fiber translocation to and the response of the pleural cavity. Amosite fibers were found to remain partly or fully imbedded in the interstitial space through 1 year and quickly produced granulomas (0 days) and interstitial fibrosis (28 days). Amosite fibers were observed penetrating the visceral pleural wall and were found on the parietal pleural within 7 days postexposure with a concomitant inflammatory response seen by 14 days. Pleural fibrin deposition, fibrosis, and adhesions were observed, similar to that reported in humans in response to amphibole asbestos. No cellular or inflammatory response was observed in the lung or the pleural cavity in response to the chrysotile and sanded particles (CSP) exposure. These results provide confirmation of the important differences between CSP and amphibole asbestos.

The pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite asbestos following short-term inhalation exposure: interim results

The pathological response and translocation of a commercial chrysotile product similar to that which was used through the mid-1970s in a joint compound intended for sealing the interface between adjacent wall boards was evaluated in comparison to amosite asbestos. This study was unique in that it presents a combined real-world exposure and was the first study to investigate whether there were differences between chrysotile and amosite asbestos fibers in time course, size distribution, and pathological response in the pleural cavity. Rats were exposed by inhalation 6 h/day for 5 days to either sanded joint compound consisting of both chrysotile fibers and sanded joint compound particles (CSP) or amosite asbestos. Subgroups were examined through 1-year postexposure. No pathological response was observed at any time point in the CSP-exposure group. The long chrysotile fibers (L > 20 microm) cleared rapidly (T(1/2) of 4.5 days) and were not observed in the pleural cavity. In contrast, a rapid inflammatory response occurred in the lung following exposure to amosite resulting in Wagner grade 4 interstitial fibrosis within 28 days. Long amosite fibers had a T(1/2) > 1000 days and were observed in the pleural cavity within 7 days postexposure. By 90 days the long amosite fibers were associated with a marked inflammatory response on the parietal pleural. This study provides support that CSP following inhalation would not initiate an inflammatory response in the lung, and that the chrysotile fibers present do not migrate to, or cause an inflammatory response in the pleural cavity, the site of mesothelioma formation.

Pursuing and Distancing: The Construct and Its Measurement

Although the concept of interpersonal pursuing and distancing has been introduced and used clinically, the lack of a reliable and valid measure has deterred its more formal investigation and relevance to personality theory. The Pursuing-Distancing (P-D) Scale, a 92-item measure of the behavioral expression of these characteristics, was developed. Evidence for internal consistency as well as internal support of construct validity is presented and discussed. An 80-item revised scale is available from the authors and is currently being evaluated in a variety of external validation settings.

A biopersistence study following exposure to chrysotile asbestos alone or in combination with fine particles

In designing a study to evaluate the inhalation biopersistence of a chrysotile asbestos that was used as a component of a joint-compound, a feasibility study was initiated to evaluate the short-term biopersistence of the chrysotile alone and of the chrysotile in combination with the sanded reformulated joint-compound. Two groups of Wistar rats were exposed to either 7RF3 chrysotile (Group 2) or to 7RF3 chrysotile combined with aerosolized sanded joint-compound (Group 3). In addition, a control group was exposed to filtered-air. The chrysotile used in the Ready Mix joint compound is rapidly removed from the lung. The chrysotile alone exposure group had a clearance half-time of fibers L > 20 microm of 2.2 days; in the chrysotile plus sanded exposure group the clearance half-time of fibers L > 20 microm was 2.8 days. However, across all size ranges there was approximately an order of magnitude decrease in the mean number of fibers remaining in the lungs of Group 3 as compared to Group 2 despite similiar aerosol exposures. Histopathological examination showed that the chrysotile exposed lungs had the same appearance as the filtered-air controls. This study uniquely illustrates that additional concurrent exposure to an aerosol of the sanded joint-compound, with large numbers of fine-particles depositing in the lungs, accelerates the recruitment of macrophages, resulting in a tenfold decrease in the number of fibers remaining in the lung. The increased number of macrophages in the chrysotile/sanded joint exposure group was confirmed histologically, with this being the only exposure-related histological finding reported.

Special-purpose fiber type 475--toxicological assessment

Type 475 special-purpose glass fiber is rather unique among the family of synthetic mineral fibers. It is used not for insulation but for "high-end" filtration products designed for high and ultra-high purity filtration of air and liquids. The designation for these types of filters varies with country and includes HEPA, ULPA, EU 10-13, EN1822, and S3. In its evaluation, type 475 has been grouped together with E-glass another special-purpose fibre often with little distinction made in terms of its chemistry and corresponding toxicological response. The detailed review of the available toxicology data on type 475 glass fibers clearly shows that following inhalation of this fiber even at relatively high doses, which likely exceed that at which lung overload in the rat is known to occur, type 475 glass fibers are not fibrogenic and do not cause tumors. These data clearly show an important differentiation in potency between type 475 glass fibers and E-glass and support treating these two types of fibers independently and not equating them though the term "special-purpose fibers." Analysis of the intraperitoneal studies taking into account fibre dimensions shows that at 109 fibers injected, there was a 0.3 tumor incidence. While these studies indicate according to the European Commission (EC) classification criteria that 475 should not be fully exonerated as a carcinogen, the results of the inhalation study fully support classification in category 3. The IP results are more difficult to interpret, however, the IP study itself provides no toxicological basis for determining what range of dose-response should correspond to EU category 3 or 2. Following the EC classification criteria, the toxicological data clearly indicate that 475 fibers are appropriately classified in EC category 3.

Biopersistence of synthetic mineral fibers as a predictor of chronic inhalation toxicity in rats

In December 1997 the European Commission (EC) adopted Directive 97/69/EC (O.J. L 343/19 of 13 December 1997) in which criteria were established for the classification and labeling of synthetic mineral fibers. This directive was derived based upon an extensive program evaluating current scientific knowledge on fiber pathogenicity and its relationship to the biopersistence of long fibers. Within this context, the biopersistence of fibers longer than 20 microm was found to be a good predictor of the lung burden and early pathological changes in chronic inhalation studies with fibers as well as of the tumor response in chronic intraperitoneal studies with fibers. The analysis that provided the scientific basis for the relationship of biopersistence to the chronic inhalation results is presented in detail. Proportional odds regression techniques were used to determine the relationship between both inhalation and intratracheal instillation biopersistence clearance half-times and the collagen deposition at the broncho-alveolar junction as determined following 24 mo in chronic inhalation toxicity studies. The results indicate all the indicators of biopersistence considered are equally good predictors of the early long-term change that occurs in the lung in response to more durable fibers. This change, the collagen deposition at the broncho-alveolar junction, is a precursor of interstitial fibrosis, which has been shown to be associated with tumor response in fiber-exposed animals. The results show that the clearance half-times set in the EC directive are within the baseline for this parameter.

Biopersistence of synthetic mineral fibers as a predictor of chronic intraperitoneal injection tumor response in rats

In December 1997 the European Commission (EC) adopted Directive 97/69/EC (O.J. L 343/19 of 13 December 1997), in which criteria were established for the classification and labeling of synthetic mineral fibers. This directive was derived based upon an extensive program evaluating current scientific knowledge on fiber pathogenicity and its relationship to the biopersistence of long fibers. Within this context, the biopersistence of fibers longer than 20 microm was found to be a good predictor of the lung burden and early pathological changes in chronic inhalation studies with fibers as well as of the tumor response in chronic intraperitoneal studies with fibers. The analysis that provided the scientific basis for the relationship of biopersistence to the chronic intraperitoneal (ip) results is presented in detail. Analysis of the relationship of biopersistence clearance half-times to ip tumor response shows a statistically significant relationship of ip tumor response to not only the number of fibers injected, but also the median length of the fibers injected and their solubility (clearance half-time). The results show that the biopersistence half-times as determined by intratracheal instillation (T(1/2) of WHO fibers or weighted T(1/2) of fibers with L > 20 microm) and as determined by inhalation (weighted T(1/2) of fibers with L > 20 microm) are equivalent predictors of the ip results. From these ip studies, fibers that can be exonerated from classification as carcinogens in Europe have a relative tumorigenic potency in the ip cavity of between 66 and 2500 times less than fibers that have been shown to produce a significant increase in tumors following chronic inhalation exposure. In addition, based upon the ip results, there is no statistical difference between the EC and the other fiber exoneration criteria, such as the German Gefahrstoffverordnung of 1999.

The current status of electrophysiologic procedures for the assessment of mild traumatic brain injury

DESIGN

This review examines studies that used spontaneous electroencephalography (EEG), evoked potentials (EP), event-related potentials (ERP), and magnetoencephalography (MEG) to detect brain dysfunction in mild traumatic brain injured (MTBI) subjects.

CONCLUSIONS

The following conclusions are offered: (1) standard clinical EEG is not useful; however, newer analytical procedures may be proven valuable; (2) consistent with current theory of MTBI, cognitive ERPs seem to be more sensitive to injury than EPs; (3) development of an assessment battery that may include EEG, EPs, ERPs, and neuropsychologic testing is advocated.

P300 event-related potential decrements in well-functioning university students with mild head injury

We compared the performance of 10 well-functioning university students who had experienced a mild head injury (MHI) an average of 6.4 years previously and 12 controls on a series of standard psychometric tests of attention, memory, and thinking and on a series of auditory oddball vigilance tasks to which we also took event-related potentials (ERPs). The MHI and Control groups performed equivalently on all the psychometric tasks and on self-report questionnaires of everyday memory and attention difficulties. The MHI group performed more slowly and with lower accuracy on only the most difficult of the oddball tasks, yet they showed substantially and significantly reduced P300 amplitudes and subsequent attentuation on all the oddball tasks, both easy and difficult. There were no alterations of N1, P2, and N2 components. These data suggest that despite excellent behavioral recovery, subtle information processing deficits involving attention nevertheless may persist long after the original injury and may not be apparent on a variety of standard psychometric measures.

Recovery from mild head injury

The subjective and objective sequelae accompanying mild head injury (MHI) are discussed in an attempt to clarify MHI's immediate and long-term consequences. Areas covered included epidemiology, classification, the post-concussive syndrome (PCS), malingering, extent of recovery, rehabilitation and guidelines for clinical practice. Special emphasis is placed on the poor relationship between subjective complaint and objective measures of impairment. Also discussed are some of the methodological problems in the MHI literature, including attempts to match MHI subjects and controls with respect to cognitive and emotional complaint and the possible confounding effects of practice. The evidence for long-lasting (i.e. more than 1 year), subtle neurobehavioral impairment after MHI indicates that additional research is required on MHI 1 year or more after injury.

Biopersistence of synthetic vitreous fibers and amosite asbestos in the rat lung following inhalation

Fiber biopersistence as a major mechanism of fiber-induced pathogenicity was investigated. The lung biopersistence of 5 synthetic vitreous fibers (SVFs) and amosite asbestos was evaluated using the rat inhalation model. In contrast to several previous studies, this study examined fibers that dissolve relatively slowly in vitro at pH 7.4. Fisher rats were exposed for 5 days by nose-only inhalation to refractory ceramic fiber (RCF1a), rock (stone) wool (MMVF21), 2 relatively durable special application fiber glasses (MMVF32 or MMVF33), HT stonewool (MMVF34), amosite asbestos, or filtered air. Lung burdens were analyzed during 1 year post-exposure. Fiber aerosols contained 150-230 fibers/cc longer than 20 micrometer (>20 micrometer). On post-exposure Day 1, long-fiber lung burdens for the 6 test fibers were similar (12-16 x 10(5) fibers/lung >20 micrometer). After 1 year, the percentage of fibers >20 micrometer remaining in the lung was 0.04-10% for SVFs but 27% for amosite. Lung clearance weighted half-times (WT1/2) for fibers >20 micrometer were 6 days for MMVF34, 50-80 days for the other 4 SVFs, and >400 days for amosite. This study and 3 previous studies demonstrate a broad range of biopersistences for 19 different SVFs and 2 asbestos types. Ten of these fibers also have been (or are being) tested in chronic inhalation studies; in these studies, the very biopersistent fibers were carcinogenic (amosite, crocidolite, RCF1, MMVF32, and MMVF33), while the more rapidly clearing fibers were not (MMVF10, 11, 21, 22, and 34). These studies demonstrate the importance of biopersistence as an indicator of the potential pathogenicity of a wide range of fiber types.

Evaluation of the oncogenic potential of man-made vitreous fibres: the inhalation model

A rodent inhalation model has been developed for the evaluation of the eoncogenic potential of man-made vitreous fibres. It is successful in delivering a quantified dose of well-characterized fibres to the lungs of rodents, and with it sufficiently high fibre aerosol concentrations were lofted to enable a maximum tolerated dose to be achieved. Fischer 344 male rats were exposed to a well-defined rat-respirable aerosol at concentrations for MMVF of 30, 16 or 3 mg m-3, 6 h per day, 5 days per week for 104 weeks with final sacrifice at 20% survival. A control group was exposed to filtered air. The high dose was chosen based upon a 28-day maximum tolerated dose study with refractory ceramic fibres (RCF). The fibre aerosol generation system lofted fibres without breaking, grinding or contaminating the bulk material. Exposure was by flow-past nose-only systems which provided fresh fibre in a laminar stream to each animal individually. The study was performed according to the Good Laboratory Practice regulations. Fibre count, fibre diameter and length distribution, aerosol mass and chemical composition were determined throughout the study. Interim sacrifices were performed at 3 or 6 month intervals for 24 months. At each sacrifice, full necropsy was performed, the accessory lobe removed for subsequent digestion to determine the fibre lung burden and the remaining lobes inflated with fixative for histopathological evaluation. The lungs were evaluated by a pathologist and graded for the degree of macrophage infiltration, bronchiolization, fibrosis and pleural thickening, and were also scored according to the Wagner scale. Lesions were evaluated according to the number of adenomas, carcinomas and mesotheliomas. The accessory lobe was digested by low-temperature plasma ashing and the number, size distribution and chemical composition of the fibres determined. This model provides a sensitive and reproducible method for evaluating existing and new fibres. A variety of different of ceramic, glass, rockwool and slagwood fibres have been evaluated with this model.

Relationship between lung biopersistence and biological effects of man-made vitreous fibers after chronic inhalation in rats

This article describes the relationship between fiber biopersistence and the chronic toxicity of different chemical compositions of man-made vitreous fibers (MMVF) in the lung. Rats were exposed in "nose-only" inhalation chambers, 6 hr/day, 5 days/week, for 24 months to aerosol concentrations of 30 mg/m3 containing comparable fiber numbers and similar dimensions of fibrous glass (FG) or refractory ceramic fiber (RCF). Interim sacrifices were performed periodically to monitor fiber number and dimensions in the lung and the progression of pulmonary alterations. At each interim sacrifice, three to six recovery animals were removed from each exposure group and held until two years to determine the biopersistence of fibers after different exposure times. Fibers were recovered from the ashed lungs, counted, and measured using optical and scanning electron microscopy (SEM). Fiber chemistry was assessed in 91-week recovery lungs using energy dispersive spectroscopy (EDS) analysis. RCF induced lung fibrosis and an elevation in lung tumors and pleural mesotheliomas. FG exposure resulted in no lung fibrosis, no statistically significant increase in the lung tumor incidence, and no mesotheliomas. After two years of continuous exposure, the number of World Health Organization fibers per milligram dry lung recovered from RCF and FG exposed lungs was comparable. EDS analysis of recovery lungs showed that most of the alkalis and alkaline earths had leached from the FG fibers over time. A slight change in RCF chemistry was observed. These findings indicate that the change in the chemical composition of fibers may be an important determinant of the chronic toxicity of MMVFs.

An experimental approach to the evaluation of the biopersistence of respirable synthetic fibers and minerals

The biopersistence of fibers and minerals in the respiratory tract is an important parameter in the toxicity of those materials. The biopersistence of respirable synthetic fibers and minerals in man can be most closely evaluated in an animal model. While acellular and in vitro systems are important for initial evaluation of solubility and durability, they cannot simulate the dynamics of inhalation deposition and clearance and the subsequent systemic reaction to fibers and minerals that occurs in the animal. To evaluate the biopersistence of synthetic fibers, male rats were exposed to a well defined rat respirable aerosol of man-made vitreous fibers (MMVF), 6 hr/day for 5 days. Following exposure, subgroups were sacrificed at intervals ranging from 1 hr to 52 weeks. Following sacrifice, the lungs were removed, weighed, and immediately frozen at 20 degrees C for subsequent digestion by low temperature plasma ashing. The number, size distribution, and chemical composition of the fibers in the aerosol and lung were determined. With this animal model the role of biopersistence in altering the geometry and clearance of fibers can be systematically evaluated. The model also can be applied for the evaluation of the biopersistence of nonfibrous minerals.

Chronic inhalation and biopersistence of refractory ceramic fiber in rats and hamsters

Lifetime "nose-only" inhalation studies were conducted in rats using four types of refractory ceramic fibers (FCF), 1 micron in diameter x 22 to 26 microns length: High Purity, Kaolin, Zirconia, and After-Service; and on hamsters using Kaolin RCF. For comparison, animals also were exposed to chrysotile fibers. Rats were exposed 6 hr/day, 5 days/week for 24 months to concentrations ranging between 3 and 30 mg/m3. Time- and dose-dependent lesions in the rat included the development of interstitial fibrosis, pleural fibrosis, pulmonary tumors, and mesothelioma. Exposure to 3, 9 or 16 mg/m3 produced no excess lung tumors; no fibrosis was seen at 3 mg/m3. A significant increase in lung tumors and interstitial fibrosis was observed at 30 mg/m3. A single mesothelioma was observed in rats exposed to 9 mg/m3, while two occurred at 30 mg/m3. Hamsters were similarly exposed to 30 mg/m3 Kaolin RCF for 18 months; no lung tumors were induced, but pulmonary and pleural fibrosis were observed and there was a 42% incidence of mesothelioma. Multiple interim sacrifices together with recovery animals allowed detailed assessment of the lung burden of RCF, which was found to be dose related and, at the high doses, exceeded 10(5) fibers/mg of dry lung. During the various recovery periods there was a clear reduction in fiber burden. Mathematical modeling of these data for deposition, clearance, and retention and for species is currently underway.

Chronic inhalation toxicity of size-separated glass fibers in Fischer 344 rats

This study was initiated to determine the chronic biological effects in Fisher 344 rats of inhaled size-separated respirable fractions of fibrous glass (FG) having compositions representative of common building insulation wools. Rats were exposed using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 24 months to three concentrations (3, 16, and 30 mg/m3) of two different compositions of FG (designated MMVF 10 and MMVF 11), or to filtered air (negative control). Fibrous glass findings were compared to those from a concurrent inhalation study of chrysotile asbestos and refractory ceramic fiber (RCF). The FGs used in this study were size selected to be largely respirable in the rat and the aerosol generation technique did not alter the dimensions of the fibers. Interim euthanizations took place at 3- to 6-month intervals to monitor progression of pulmonary changes. Fibers were recovered from digested lung tissue for determination of changes in fiber number and morphology. In animals exposed to 30 mg/m3 of MMVF 10 or MMVF 11, 4.2 +/- 0.9 x 10(5) and 6.4 +/- 3.1 x 10(5) fibers/mg dry lung tissue, respectively, were recovered after 24 months of exposure. Exposure to chrysotile asbestos (10 mg/m3) and to a lesser extent RCF (30 mg/m3) resulted in pulmonary fibrosis as well as mesothelioma and significant increases in lung tumors. FG exposure was associated with a nonspecific inflammatory response (macrophage response) in the lungs that did not appear to progress after 6-12 months of exposure. These cellular changes are reversible and are similar to the effects observed after inhalation of an inert dust. No lung fibrosis was observed in the FG-exposed animals. Further, FG exposure resulted in no mesotheliomas and no statistically significant increase in lung tumor incidence when compared to that of the negative control group. These findings, along with previous inhalation studies, suggest that respirable fibrous glass does not represent a significant hazard for fibrotic or neoplastic lung disease in humans.

Evaluation of cutaneous responses and lung function from exposure to opiate compounds among ethical narcotics-manufacturing workers†

We recently demonstrated morphine-6-hemisuccinate-human serum albumin conjugate (M-6-HS-HSA)-specific IgG in serum from ethic narcotics-manufacturing workers. In this article, we present results of epicutaneous tests to opiate compounds and lung-function studies in these same workers. Thirty-nine workers, exposed to opiates, were evaluated for possible work-related changes in lung function and were administered a questionnaire concerning opiate exposure and health history in February 1988. In December 1988, 33 employees with occupational exposure to opiates, six other workers (New Jersey referent) employed at the same factory with minimal exposure to opiate compounds, and 17 nonexposed individuals from Cincinnati, Ohio, were subjected to epicutaneous threshold testing with a panel of six opiate compounds and nine common aeroallergens. In opiate-exposed workers, significantly lower epicutaneous threshold concentrations were detected (compared to New Jersey referent and Cincinnati control subjects) for dihydrocodeine (p less than 0.01), hydrocodone (p less than 0.05), codeine (p less than 0.01), and morphine (p less than 0.05). Significant associates existed among epicutaneous threshold concentrations between the agents tested; that is, individuals with a positive morphine skin test would generally have a positive codeine skin test, etc. Atopic status (positive cutaneous test results to two or more of nine common aeroallergens) was not significantly associated (p greater than 0.05) with positive opiate skin sensitivity. Although the mean cross-shift decrements in FEV1 for all workers were nonsignificant, five opiate-exposed individuals demonstrated cross-shift decrements in FEV1 of greater than 10%. Daily maximum-minus-minimum changes in workweek PEFR (PEFRmax-min) were significantly reduced for Monday through Thursday (p less than 0.05) compared to PEFRmax-min changes during a nonwork, nonexposure 3-day weekend. Ten exposed workers demonstrated daily PEFRmax-min changes of greater than 20%, suggesting acute airway obstruction. Increased cutaneous reactivity to opiate compounds among opiate-exposed workers may reflect development of pharmacologic hyperresponsiveness to opiate compounds.

Safety and efficacy of a new peripheral intravenously administered amino acid solution containing glycerol and electrolytes

A multicenter study was conducted to compare a new peripheral intravenously given solution containing 3 per cent amino acids, 3 per cent glycerol and a complete pattern of maintenance electrolytes--ProcalAmine--with an isonitrogenous amino acid control solution--FreAmine III--in patients undergoing elective gastrointestinal or vascular operations. Fifty-two patients received the control solution and 48 patients received the experimental solution in a double-blind, randomized trial for five consecutive postoperative days. A complete hematologic and biochemical assessment was carried out daily throughout the five day infusion period and two days after the termination of infusion. Nitrogen balance data were collected on each infusion day. Results indicate that the glycerol containing solution is safe and contributes to an improvement in nitrogen homeostasis on a daily and cumulative basis. The presence of ketosis was not related to an improvement in nitrogen balance. In conclusion, the addition of glycerol to dilute amino acid solutions is safe and improves nitrogen balance in the postoperative period. Additionally, use of the nonreducing sugar, glycerol, allows the manufacturer to sterilize amino acids and an energy substrate in a single unit. By precluding the need for admixing in the hospital pharmacy, risk of contamination may be reduced.

The role of nuclear scanning in the evaluation of arterial injuries

Nuclear scanning appears to be a useful test to screen patients with penetrating injuries to the extremities who have proximity as the only finding suggestive of vascular injury. Patients with abnormal scans should be further studied with standard angiography. Interpretation of the scan is dependent on the reader's experience.

Selection of patients with abdominal stab wounds for laparotomy

The roles of local wound exploration (LWE) and peritoneal lavage (PL) in the selective management of stab wounds to the lower chest and abdomen were evaluated prospectively in 53 patients. Twenty-four patients underwent immediate laparotomy for obvious clinical signs of intra-abdominal injuries. Twenty-nine patients with evidence of anterior abdominal fascia penetration or equivocal LWE had PL before laparotomy. Operative findings were correlated with the preoperative assessment of LWE and PL. Twenty patients in this group had intra-abdominal injuries. All patients with positive PL were found to have an intra-abdominal injury. Six patients with a negative PL and a positive LWE had visceral injuries. Three of these injuries were considered significant with an overall false negative PL of 15%. Laparotomy performed on the basis of LWE resulted in nine patients (31%) having an unnecessary laparatomy. Careful physical examination, the results of local wound exploration, and peritoneal lavage should be considered in selecting patients with abdominal stab wound for laparotomy.

The major parameters affecting temperature inside inhalation chambers

Variations in inhalation chamber temperature can produce alterations in animal physiology, metabolism of foreign compounds as well as the chemical interaction of pollutant aerosols. This report presents the results of an investigation of the different mechanisms of heat transfer in a 380 L inhalation chamber and discusses the relative effectiveness of various methods that may be used to maintain a uniform chamber temperature during animal exposures. The thermal characteristics of the inhalation chamber were studied using an array of 40 thermocouples, with and without rats in the chamber and with and without 5 cm fiber glass insulation surrounding the chamber. Temperature profiles were measured with different animal loadings and intake air temperatures. An effective heat transfer coefficient of 6.6 +/- 1.8 W/m2 degrees C was determined for the stainless steel walls of the chamber. Heat balance studies with rats in this chamber have shown that with room air intake at a flow rate of 100 L/min, the stainless steel chamber walls were effective at removing approximately ninety percent of the animal heat as compared to the airstream.

Experimental approaches for exposure to sized glass fibers

A number of studies have shown that glass fibers induce both malignant mesothelioma and fibrosis in rats and that these reactions may be primarily a function of the physical properties of the fiber. However, these studies were carried out with fibers having broad size distributions and used methods of administration which bear little resemblance to the way man is exposed. To better characterize the health effects of glass fibers, techniques have been developed to expose rats to glass fibers of defined sizes by intratracheal instillation of aqueous suspensions and by "nose only" inhalation exposure, and to determine the deposition, translocation, and ultimate fate of these fibers in the rat. The fibers have known size distributions with geometric mean diameters of 1.5 micrometers (sigma g = 1.1) and lengths of either 5 micrometers (sigma g = 1.49) or 60 micrometers (sigma g = 3.76). The fibers have been activated with neutron irradiation. Of the several resulting radionuclides, 65Zn appeared to be the most suitable for long-term clearance studies by use of in vivo whole body radioassay techniques. A fluidized bed aerosol generator has been developed to expose rats by "nose only" inhalation to approximately 500 fibers/cm3. The generator and exposure system permits reuse of fibers which pass through the exposure chamber and produces no significant alteration of the fiber size distribution. Rats were exposed by intratracheal instillations to 20 mg of the longer fibers and to equal numbers (2 mg) and equal mass (20 mg) of the shorter fibers. Through approximately 19 weeks little difference was observed in the whole rat clearance rate of long versus short fibers in the initial exposure group. Histopathology, however, showed differences at this time with the short fibers apparently successfully phagocytized by alveolar macrophages and cleared to the lymph nodes, while the long fibers were not.

The Laskin aerosol generator

This paper describes construction details and operating characteristics of a nebulizer developed by Sidney Laskin and used over a period of 30 yr in various laboratories to generate respirable aerosols for whole-animal inhalation exposure studies. Under the proper operating conditions, the device is capable of producing nearly monodisperse aerosols in the respirable size range (1.5 micron volume median diameter with a geometric standard deviation of 1.1) for long periods of time

Legal aspects of electrotherapy in a catatonic renal transplant patient

The treatment of a case of catatonic schizophrenia in a renal transplanted patient is presented and demonstrates that electrotherapy can be life-saving and that there are already adequate legal controls which guarantee the patient's rights. Yet zealots are attempting to have legislators pass laws preventing the use of electrotherapy even in voluntary patients. To help prevent these resolutions from being passed, psychiatrists must become more active in the legislative process.